Messages in this thread | | | From | Arnd Bergmann <> | Date | Mon, 30 Dec 2019 13:34:00 +0100 | Subject | Re: [PATCH] mips: vdso: conditionalize 32-bit time functions on COMPAT_32BIT_TIME |
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On Mon, Dec 30, 2019 at 1:27 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote: > > On Mon, Dec 30, 2019 at 12:58 PM Arnd Bergmann <arnd@arndb.de> wrote: > > Thanks for the bug report! I'm not completely sure why this fails in > > this particular > > way though. I assume you are using musl-1.1.20, not a musl-1.2.0 snapshot > > Yes, that's the one, sorry. > > > diff --git a/arch/mips/vdso/vdso.lds.S b/arch/mips/vdso/vdso.lds.S > > index da4627430aba..0bdc6a026be8 100644 > > --- a/arch/mips/vdso/vdso.lds.S > > +++ b/arch/mips/vdso/vdso.lds.S > > @@ -93,9 +93,11 @@ VERSION > > LINUX_2.6 { > > #ifndef DISABLE_MIPS_VDSO > > global: > > +#if (_MIPS_SIM == _MIPS_SIM_ABI64) || defined(CONFIG_COMPAT_32BIT_TIME) > > __vdso_clock_gettime; > > __vdso_gettimeofday; > > __vdso_clock_getres; > > +#endif > > #if _MIPS_SIM != _MIPS_SIM_ABI64 > > __vdso_clock_gettime64; > > #endif > > > > That should ensure that no user space can call the old vdso > > functions on a kernel that intentionally breaks the actual > > syscalls. > > I can confirm that patch fixes things. Thanks.
Ok, that's good news, but I think we still need to answer two questions:
- Why does it crash in the first place rather than returning -ENOSYS?
- How does it actually work if you run an application built against an old musl version on a kernel that tries to make this not work? Do you just get a random time (uninitialized user space stack) and work with that without checking the error code?
Arnd
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